A widely used embodiment of a signal transformation arrangement is a mixer. Up- or down-mixing is used to convert a signal between radio frequency and base-band level. In addition to an input signal, a local oscillator signal may be applied to the mixer. The input signal is often processed in the mixer by a multiplication with an ideal sine-wave local oscillator signal.
Document U.S. Pat. No. 7,043,222 B2 shows a modulator using up-mixers and sine-wave coded digital-analog converters.